The influence of different composite placement techniques on microleakage in preparations with high C- factor: Anin vitrostudy

Abstract

Objective:This study evaluated the marginal leakage around class-I cavity preparations restored with Nanofilled composite (Filtek Z-350 A2 shade, 3M ESPE, USA) and a self-etch adhesive (Xeno III, DENTSPLY/Caulk) using different composite placement techniques.Materials and Methods:Standardized class-I cavities were prepared on 36 caries-free, extracted human premolars and were randomly assigned to three groups: (1) Horizontal incremental curing was done; each increment of thickness 1.5 mm was cured one after the other using curing unit (T-LED, Elca Technology, Italy). (2) Concave surface was obtained with a ball burnisher on the first increment and cured for 20 seconds; subsequently, the next increment was placed and similarly cured. (3) Cavities were filled with resin, short of the occlusal surface; two cuts (mesiodistal and buccolingual) were made through the condensed resin and cured for 20 seconds, followed by addition of resin in the gaps created by the cuts and additional curing for 20 seconds. The specimens were stored in distilled water for three months and then subjected to thermocycling, followed by immersion in 0.5% methylene blue dye for 24 hours. The teeth were sectioned longitudinally and evaluated for microleakage under stereomicroscope, and the scores obtained were analysed with Fisher Exact test and Kruskal-Wallis nonparametric test.Results:There was no statistically significant difference among three groups.Conclusion:None of the techniques was capable of eliminating the microleakage in preparations with a high C-factor.

Comparative Evaluation of Microleakage in Class 2 Cavities Restored with A Nanohybrid Composite Using Three Different Increment Techniques- An in vitro Stereomicroscopic Study

“…The second layer in the oblique technique, which was also a diagonal layer, was not able to cover the first diagonal layer in the cervical area, which did occur with the second layer of the centripetal build up technique (15). Duarte S et al (2008) (10) reported that polymerization shrinkage was less in the centripetal technique compared to oblique incremental technique. Though the results of these two techniques of composite placement were statistically insignificant but centripetal technique showed less microleakage then the oblique increment, probably because the number of increments used were more with centripetal technique (5 increments) than oblique techniques (4 increments).…”

“…Control of polymerization shrinkage stresses during a direct composite resin restoration is important for achieving a perfect adaptation between restoration and cavity wall. In order of importance, the factors involved in shrinkage stresses are cavity C-factor, cavity size, incremental technique, intensity and position of curing light, and properties of composite (10). In this study, attempts were made to keep all these variables constant, except for the composite placement technique.…”

Evaluation of marginal microleakage in composite restorations with different placement techniques

“…Santhosh et al investigated whether the modification of the horizontal incremental method was beneficial in terms of C-factor, which is effective for polymerization shrinkage stress and therefore microleakage (25). Three different methods -the classical horizontal incremental technique (gingivoocclusal), concave surface formation and split technique -were compared in Class I cavities with a high C-factor and no statistical difference was found between methods in terms of microleakage.…”

Influence of Surface Sealants on Microleakage in Composite Restorations

“…Thus, microleakage associated with polymerization shrinkage is a major drawback of resin composites, since the resulting shrinkage stress can cause microgap formation at the resin-enamel interface. Indeed, microleakage is one of the most cited reasons for failure of composite resin restorations (Dickinson & Leinfelder, 1993;Davidson & Feilzer, 1997;Santhosh et al, 2008). The shrinkage stresses generated during polymerization can lead to loss of marginal adaptation, resulting in adhesion failure and microgap formation.…”